1. Field of the Invention
The present invention relates to a stable aqueous suspension liquid of ultradispersed diamond particles having particle size of, for instance, 4.2 nm or less in average diameter (which may also be referred as UDD or namodiamond hereinafter in this specification), and a diamond powder of UDD obtained from said aqueous suspension liquid, metallic film containing the UDD particles and preparation method of the aqueous suspension liquid and the metallic film.
In general, these UDD particles have 2 nm to 70 nm of diameter, definitively 2 nm to 40 nm of diameter, and in case of the dry powder obtained from the aqueous suspension liquid, several to thousands primary UDDs pareticles, generally, tens to hundreds primary UDDs pareticles are being quasi-aggregated and having a numeral average diameter of 150 to 600 nm and bigger particles having more than 1000 nm of diameter and smaller particles having less than 30 nm of diameter are rare.
2. Description of the Related Art
It is known that preparation method of fine diamond particles called ultra dispersed diamond (UDD), in which by imposing shock waves to a carbonaceous material, UDD are produced. For instances, Japanese Examined Patent Publications of Tokkou Shou 42-19684, Tokkyou Shou43-4641, Japanese Unexamined Patent Publications of Tokkai Shou 46-1765, Tokkai Shou 50-157296 disclose that diamond-like fine particles are produced by imposing an impulse voltage formed between a pair of opposite electrodes to a carbon material placed in high pressure and high temperature liquid. And Japanese Unexamined Patent Publications of Tokkai Shou 48-3759, Tokkai Shou 48-8659, Tokkai Shou49-8486 Tokkai Shou 49-39595, Tokkai Shou 49-51196, Tokkai Shou 50-149595, Tokkou Shou 53-30969, Tokkai Shou 54-4298, Tokkai Shou 55-56007, Tokkai Shou 55-56829, Tokkai Shou 55-90410, Tokkai Shou 57-194040, Tokkai Shou 60-48133, Japanese Unexamined Patent Publication of Tokkai Hei 4-83525, Japanese Examined Patent Publications of Tokkou Hei 1-14994 disclose that diamond-like fine particles are produced by imposing a super high pressure of shock waves which are generated by detonation of explosive, to a carbon material. Japanese Unexamined Patent Publication of Tokkai Hei 1-234311 discloses a producing method of synthetic diamond which comprises steps of holding a high vacuum state in a tubular reaction container made of quartz, producing a crude diamonds by using a detonation synthesis technique, exposing the crude diamonds to oxygen plasma gas at a low temperature for oxidizing combustible carbonaceous powder contents to a gas phase, and separating synthetic diamonds from the tubular reaction container.
As shown in FIG. 31 (which is, for just scientific reference, a copy cited from the Bull. Soc. Chim. Fr. Vol. 134 (1997), pp. 875–890), fine diamond particles synthesized by such a shock imposing method may commonly exhibit some prominent reflective intensity peak at 26.5±2° of the Bragg angle (2θ) implying the presence of not transformed graphite structure, in addition to common peak 44±2° of the Bragg angle (2θ) pertinent to a (111) crystal structure of diamond, in the X-ray diffraction (in scanning with Cu-K α radiation at 30 kV of bulb potential and 15 mA of bulb current).
Japanese Unexamined Patent Publication of Tokkai Hei 2-141414 discloses a synthesis process of diamond in which the process is executed by steps of forming a source material composition 10 g consisting of 80% of an explosive (hexogen), 14.2% of graphite and 5.8% of paraffin, to a cylindrical form having 2 cm diameter and 1.47 g/cc density, placing the cylindrical form of source material composition, into the inside space of a tube having side end opening or side ends openings, attaching 1.5 g of hexogen and a No.6 electric detonator to the cylindrical form of the source material composition, then detonating the cylindrical form of the source material composition which being sunk at a depth of one meter in an inverted cone shaped water tank container sized 1.5 m in diameter and 2 m in height and the detonations are repeated 10 times to sum up to total detonated amount 100 g, treating the reaction product with nitric acid, and a mixture of hydrochloric acid and nitric acid, and a mixture of hydrofluoric acid and nitric acid, respectively, then washing plural times with waters and drying the obtained material, to obtain synthesized diamond which has no peak at the Bragg angle (2θ) of 26.5±2°, by 11.5% yield.
With regard to characteristics of diamond obtained by explosive shock method, “Science”, Vol. 133, No. 3467, pp. 1821–1822, published in June of 1961 by the American Association for the Advancement of science, Washington, describes that to study of the effects of explosive shocks on various minerals, samples of spectro-scopically pure artificial graphite were exposed to shock pressures estimated at 300,000 atm for 1μ sec, and the recovered fragments, which were microscopically resembled with the original material, were rather brittle and did not possess greasy texture of normal graphite powder when ground in a mortar, and X-ray diffraction pattern of the shocked graphite showed three additional lines, weak and slightly broadened, which could be indexed as (111), (220), and (311) these are only possible reflections from diamond, and specimen ground and centrifuged in bromoform showed density 2.87 μl cm3 which is a mean value between 2.25 g/cm3 pursuant to graphite and 3.5 g/cm3 pursuant to diamond, and the distance between bonded atoms in the diamond component is 2.06 angstroms which is very different from 3.35 angstroms of the distance between graphite atoms.
FIG. 32 (which is, for just scientific reference, a copy cited from Bull. Soc. Chim. Fr., Vol. 134 (1997), pp. 875–890) illustrates pressure/temperature dependent profiles of carbon at diamond phase, graphite phase, and liquid phase.
According to “Effect of hydrogen in ultradisperse diamond structure”, Physics of the Solid State, Vol. 42, No. 8 (2000), pp. 1575–1578 and “Structure and defects of detonation synthesis nanodiamond”, Diamond and Related Materials, Vol. 9 (2000), pp. 861–865, UDD synthesized by the shock conversion method is in the form of aggregates of fine particles having 40 to 50 angstroms diameter and 100 nanometers at the maximum, and each UDD particle consists of a lattice core of sp3 carbons which is wrapped with a shell of active sp2 carbons having 4 to 10 angstroms thickness.
Also, depicted in “Chemical Physics Letters”, 222, pp. 343–346, published in May of 1994, onion-like carbon from ultra disperse diamond (UDD) denotes that the detonation samples were prepared from 50/50 TNT/RDX (trotyl/cyclotrimethylene-trinitramine) by igniting fire shock in a hermetic tank, and the UDD (with 3.0 to 7.0 nm in the diameter, 4.5 nm in the average diameter) have been isolated from the detonation soot by oxidative removal of non-diamond carbon with HClO4,, the elementary cell parameter of the UDD α=0.3573 nm (0.35667 nm for bulk diamond), and an elemental analysis of the UDD has shown a relatively high concentrations of hydrogen-, nitrogen- and oxygen-containing groups which could be partially removed from the sample by heating in vacuum, however, a potion of such elements are possibly included in the annealed products, and denotes that the UDD annealing was performed in a tantalum cap heated by an electronic beam at 1000–1500° C., which was placed in a high-vacuum chamber, and from XRD data of the UDD, the distance of faces between the (111) reflections (lattice parameter) of this UDD was 0.2063 nm (for bulk diamond d111=0.205 nm), and by such heating, surface energy of the UDD was decreased therefore the volume of the UDD was dramatically increased from 2.265 g/m3 to 3.515 g/m3, due to the extinction of dangling bonds, and in case of the number of surface atoms of each UDD particle is not large enough to form a completely closed spherical graphite network, the carbon atoms form an onion-like shape consisting of concentric fullerene shells, and the most stable, octagonal lattice of resultant diamond crystals consists of 1683 carbon atoms having a diameter of 2.14 nm, in which 530 carbon atoms are the surface atoms, and in comparison, a cubic crystal form of diamond of the same size has 434 carbon atoms as the surface atoms.
In general, element analysis of UDD implies the presence of hydrogen contained groups, nitrogen contained groups, and oxygen contained groups, however it does not identify the detailed kind and quantity of the groups.
Carbon, Vol. 33, No. 12 (1995), pp. 1663–1671 reporting FTIR Study of ultradispersed diamond powder synthesized by shock conversion”, describes that UDD synthesized in a reaction mixture of carbon, micro-graphite, carbon black and so forth, by detonation of a carbon-containing explosive which includes a significantly negative balance of oxygen atoms than chemically equivalent amount of oxygen to react with carbon atoms and other oxidative atoms in the chemical structure of the explosive, has highly defective structural surfaces, high activity and absorptivity which were inspected by various techniques such as differential thermal analysis, mass-spectrum analysis, gas chromatography, polarography, X-ray photoelectric spectroscopy, TEM, or IR spectroscopy (1. V. I. Trefilov, G. I. Savaakin, V. V Skorokhod, Yu. M. Solonin and B. V. Fenochka, Prosh. Metall. (in Russian), Vol. 1, No. 32 (1979); 2. N. R. Gneiner, D. S. Phillips, J. D. Johnson and F. Volk, Nature, 333(6172) and 440(1988); 3. A. A. Vereschagin, G. V. Sakovich, A. A. Petrova, V. V. Novoselov and P. M. Brylyakov, Doklagy Akademii Nauk USSR, 315,104(1990) (in Russian); 4. A. A. Vereschagin, G. M. Ulyanova, V. V. Novaselov, L. A. Petrova and P. M. Brylyakov, Sverkhtverdyi Materialy, 5,20(1990) (in Russian); 5. A. L. Vereschagin, G. V. Sakovich, V. F. Kamarov, and E. A. Petrov, Diamond Relat. Mater. 3,160 (993); 6. B. I. Reznik, Yu. M. Rotner, S. M. Rotner, S. V. Feldman, and E. M. Khrakovskaya, Zh. Prikl. Spektr. 55,780 (1990) (in Russian); 7. F. M. Tapraeva, A. N. Pushkin, I. I. Kulakova, A. P. Rydeko, A. A. Elagin, and S. V. Tikhomirov, Zh. Fiz. Khimii 64,2445 (1990) (in Russian); 8. V. K. Kuznetsov, M. N. Aleksandrov, I. V. Zagoruiko, A. L. Chuvilin, E. M. Moroz, V. N. Kolomiichuk, V. A. Likholobov, and P. N. Brylyakov, Carbon 29,665 (1991); 9. V. F. Loktev, V. I. Makalskii, E. V. Stoyanova, A. V. Kalinkin, V. A. Likholobov, and V. N. Michkin, Carbon 29,817 (1991); 10. T. M. Gubarevich, V. F. Pyamerikov, I. S. Larionova, V. Yu. Dolmotov, R. R. Samaev, A. V. Tyshetskaya, and L. I. Poleva, Zh. Prikl. Khimii 65,2512 (1992) (in Russian); 11. G. A. Chigonova, A. S. Chiganov, and Yu. V. Tushko, Zh. Prikl. Khimii 65,2598 (in Russian); 12. D. S. Knight and W. B. White, J. Mater. Res. 4,385 (1989); 13. P. V. Huong, J. Molec. Structure 292,81 (1993); 14. B. Dischler, C. Wild, W. Muller-Sebert, and P. Koild, Physica B 185,217 (1993); 15. T. Ando, S. Inoue, M. Ishii, M. Kano, and Y. Sato, J. Chem. Soc., Farad. Trans. 89.749 (1993); and 16. T. Ando, M. Ishii, M. Kano, and Y Sato, J. Chem. Soc., Farad. Trans. 89,1783 (1993).
This literature also says that the IR spectroscopic measurements are however scarcely denoted heretofore.
It is also described in this literature that the UDD obtained by a detonation method shown in Energetic Materials 1,19 (1993) (in Chinese) by K. Xu. Z. Jin, F. Wei and T. Jiang, and subjected to (1) removing process to remove metal impurities using 18% HCl for one hours, decanting with water, dry distilling with a mixture of HClO4(71%):HNO3(65%)=6:1 at 200° C. for two hours until their color turns from black to thin brown, and having 250 to 270 m2/g of specific surface and 3.3 g/cm3 of density by a BET technique, elemental content of 85.87% of carbon, 1.95% of nitrogen, 0.60% of hydrogen, 0.16% of sulfur, and less than 11% of oxygen and has an initial drying loss of 0.37%, exhibits its IR absorption spectrum characteristics as shown in FIGS. 33 to 36 (which is, for just scientific reference, copies cited from this “Carbon”, Vol. 33, No. 12 (1995), pp. 1663–1671), where the resultant product being denoted by the real lines and its profile after heated at 140° C. for five hours being denoted by the dotted lines, and in FIG. 34 illustrating an enlarged portion from 3700 cm−1 to 3000 cm−1 of the deconvoluted spectrum profile of FIG. 37, FIG. 35 which are illustrating another enlarged portion from 1900 cm−1 to 1500 cm−1 of the same profile, FIG. 36 which is illustrating a further enlarged portion from 1500 cm−1 to 900 cm−1 of the same profile); And alternatively, another UDD subjected to (II) removing metal impurities with the use of 18% HCl for one hours, decanting with water, dry distilling with a mixture of H2SO4(98%):fuming sulfuric acid, SO3(less than 50%): HNO3(65%)=2:1:1 and a small amount of HCl at 270° C. for two hours until their color turns from black to thin brown, and having elemental content of 87.58% of carbon, 2.14% of nitrogen, 0.62% of hydrogen, 0.00% of sulfur, and less than 10% of oxygen and has an initial drying loss of 0.127% by weight, exhibits its IR absorption spectrum characteristics as shown in FIGS. 37 to 40 (where the resultant product being denoted by the real lines and its profile after heated at 140° C. for five hours being denoted by the dotted lines, FIG. 38 which is illustrating an enlarged portion from 3700 cm−1 to 3000 cm−1 of the deconvoluted spectrum profile of FIG. 37, FIG. 39 which are illustrating another enlarged portion from 1900 cm−1 to 1500 cm−1 of the same profile, FIG. 40 which is illustrating a further enlarged portion from 1500 cm−1 to 900 cm−1 of the same profile).
It is also described in this literature that IR spectra of aforementioned UDD (I) which was dressed by aforementioned treatment (I), and aforementioned UDD (II) which was dressed by aforementioned treatment (II) are identified as shown in TABLE 1, depending upon D. Lin-Vien, N. B. Colthup, W. G. Fateley, J. G. Grasselli, “The hand book of infrared and Raman characteristic frequencies of organic molecules”, Academic Press, Boston (1991); K. Nakanishi, P. H. Solomon, “Infrared absorption spectroscopy, 2nd edition”, Holden Day Inc., San Francisco, Calif. (1977); A. D. Cross, “Introduction to practical infrared spectroscopy, 3rd edition”, Butterworth, London (1964); F. M. Tapraeva, A. N. Pushkin, I. I. Kulakova, A. P. Rydenko, A. A. Elagin and S. V. Tikhomirov, “Zh. Fiz. Khimii (in Russian)”, 64,2445 (1990)(concluding that the absorptivity of 1733–1740 cm−1 is based on ═CO, —COH, —COOH); V. K. Kuznetsov, M. N. Aleksandrov, I. V. Zagoruiko, A. L. Chuvilin, E. M. Moroz, V N. Kolomiichuck, V. A. Likholobov, and P. N. Brylyakov, “Carbon”, 29,665 (1991)(concluding that the absorptivity of 1733 cm−1 and 1670 cm−1 by UDD is based on COO—); R. Sappok and H. P. Boehm, “Carbon”, 6,283 (1968)(concluding that the absorptivity of 1742 cm−1 is based on a ketone group of cyclohexanone and the absorptivity of 1772 cm−1 is based on a ketone group of cyclopentanone, the absorptivity of 1760 cm−1 may equally be based on a ketone group); and T. Ando, S. Inoue, M. Ishii, M. Kato, and Y. Sato, “J. Chem. Soc., Farad. Trans. 89,749 (1993)” (concluding that the absorptivity of 1760 cm−1 is based on a carbonyl group of cyclic carbonic aid anhydride).
It is also noticeable that this literature, with referencing above cited many reports and literatures, says that repeated purification of the UDD with (I) various mixtures of perchloric acid-nitric acid—hydrochloric acid, or (II) various mixture of sulfuric acid nitric acid-fuming sulfuric acid, are worth nothing for the UDD, when they have been treated with hydrochloric acid to remove metallic impurities then with such kinds of acid mixtures, even if the repeated treatments are conducted after reduction treatment
TABLE 1Summary of main IR frequencies of UDDAbsorbance frequencyaUDD (I) and UDD (II)IIIafter reductionAssignment and RemarksSame as I, IIBonded νOHνOH, water, tertiary alcoholBonded νOH, νNH νas CH3νas CH2νs CH3, νCHνs CH2   1460wδas CH3, CH2, CH  618w~550b619w~550baThe frequencies on the right of the brackets are the frequency positions determined by deconvoluted and second-ferivative and fitted spectra. s, Strong; m, medium; sh, shoulder; b, broadbD,N-induced one-phonon process and/or defect structure in diamond
Generally speaking, fine particles of single-crystal diamond synthesized by imposing a static and ultra-high pressure onto a carbon material are relatively large in the crystalline structure and may occur particles having sharp angles if shock fracturing thereof is caused, due to whose cleavage shearing property. Very fine particles of diamond (UDD), which is synthesized by imposing an instantaneous dynamic ultra-high pressure to a carbon material, also holds more or less level of such shock fracture properties. Accordingly, as disclosed in Japanese Unexamined Patent Publication of Tokkai Hei 4-83525, such a shock conversion method using an ultra-high pressure of the shock waves generated by detonation of an explosive can be utilized for modification of already synthesized diamonds, where diamonds are embedded in a metal binder and exposed to the shock waves generated by detonation of an explosive to develop their modified form.
The element of group VIII in the Periodic Table of elements such as iron has a catalytic effect in course of the shock conversion reaction of a graphite structure into a diamond structure by detonation of an explosive, and are used as catalysts during the shock conversion of a graphite structure into a diamond structure by detonation of an explosive and this metal binder would easily provide a favorable pressure-resistant condition for receiving and withstanding for a high pressure as 10 GPa or preferably 20 GPa of pressure which is generated by the shock waves of the detonation, furthermore the metal binder is capable of a fast heat transfer for heat absorbing from and radiating to the out side of the system, therefore the metal binder can easily provide a high heat-transfer condition that enables a quick cooling of the reaction system, so that it does not make stay a UDD being once produced by a high temperature such as 3000 degree K or more, in a dangerous state apt to return the UDD to graphite by textural conversion, namely does not stay the UDD in a dangerous state that ultra high pressure of the system for UDD synthesis has already liberated while the temperature is still in high level as 2000 to 1500 degree K.
However, for removing merely metal binder to recover the produced UDD particles which having been buried in the metal binder, a worrisome treatments must be inevitable which might be comprise a removal treatment of the metal covering by cutting or destruction, a dissolving treatment by acid and so forth treatments. Thereafter, it is, of course, further required a treatment for purifying the UDD by removal of impurities such as non reacted graphite or carbon fine particles etc.
Disclosed in Japanese Unexamined Patent Publication of Tokkai Shou 63-303806 is a technique for picking up diamonds synthesized in a metal medium by shock conversion. It discloses that removal of unwanted graphite is difficult by only exposing the synthesized diamonds to fuming nitric acid or concentrated nitric acid or any other strong oxidizer which may be a mixture of hydrogen peroxide, fuming nitric acid or concentrated nitric acid and if desired, potassium permanganate, sodium chlorate, or hydrogen peroxide. Also, there is provided a technical knowledge for a purifying process in this patent document that the process consisting of pressurizing particles of a graphite material having a diameter of 0.1 mm or less and encapsulated in a catalyst metal (Fe50-Ni50 alloy) with a pressure force of 5.2 GPa at a high temperature of 1380° C. for 15 minutes, exposing their resultant aggregate to 35% hydrochloric acid at 100° C. for 3 hours to dissolve and remove the catalyst metal, and oxidizing the resultant powder from graphite to carbon dioxide with using a mixture of concentrated phosphoric acid, concentrated sulfuric acid, and concentrated nitric acid at 320° C. for 5 hours, and this oxidizing steps are repeated three times (in total 15 hours). It is also described that an examination of the product by an XRD analysis (X-ray diffraction using Cu-Kα radiation) revealed some prominent peaks of the intensity pursuant to the (111) plane diamond at 44±2° of the Bragg angle (20±2°) and other peaks indicating the presence of graphite at 26.5°, and when the product is subjected to an ultrasonic wave oxidization process using ultrasonic wave at a resonant frequency 20 KHz by a ceramic ultrasonic wave generator operated at an output power 150 W with a mixture of concentrated sulfuric acid and concentrated nitric acid at a temperature of 320° C. for one hour, and which processes are repeated five times (in total 5 hours), the crystallized diamonds are successfully separated from unwanted graphite particles, and almost all of the graphite have been disappeared by the purification process.
Another shock conversion method for synthesizing diamond powder is disclosed in Japanese Unexamined Patent Publication of Tokkai Shou 56-26711 which comprising steps of mixing a carbon precursor (organic material does not melt by heating, such as phenollic resin, furfuryl alcohol derivatives, cellulose derivatives) provided as the carbon source material with an amount not fewer than 80% by weight of a thermally conductive metal powder (if few than 80% by weight, the productivity will be declined), compressing the mixture into a shape, imposing a shock pressure of 400 to 1500 kilobars to the shaped mixture, and holding a resultant blended diamond powder for 30 minutes in a solution prepared by dissolving 0.1 mol % of sodium chlorate in concentrated nitric acid and keeping a temperature of 80° C. to dissolve and remove non-converted carbons, as a result, the diamond powder can be prepared at a higher productivity (of 60%) which is highly dressed and having a color of substantially white, and by this method, in contradiction to the known theory that the diamond structure returned back to the graphite form when the compressing pressure is smaller than 1500 kilobars, the proposed method of synthesizing fine particles of diamond can be obtained at a higher productivity, than that of a prior art method disclosed in British Patent No. 1154633 which describes:
Compressing Pressure (Kbar)Productivity (%)1,40052–3290012,780 5,on the other hand, the proposed method can synthesize diamonds at a productivity of 40% using a pressure of 1000 kilobars.
British Patent No. 1154633, which is referred in aforementioned Japanese Unexamined Patent Publication Tokkai Shou 56-26711, describes that a crude diamond product synthesized from graphite material by shock conversion method under the high enough temperature(2000° C. or more) and pressure (300 to 700 kilobars) is a diamond of particles form which are contained in pocket of substantial quantities of unconverted graphite and inorganic impurities containing silicon, iron, boron, aluminium, calcium and titanium, and from this crude diamond, a purified metallic grey lustre is obtained by purifying with moneral non-oxidising acid such as hydrochloric acid then with oxidising acid such as nitric acid at atmospheric pressure, temperatures of at least 280° C., preferably above 300° C., and this purified diamond is not greater than 0.1 μm of average diameter, 40–400 m2/g in the surface area, carbon 87% to 92%, hydrogen 0.5% to 1.5%, and not greater than 1.0% in the content of nitrogen and have acidic, and has least 20% of hydrophilic surfaces bonded with functional groups such as hydroxy functional group, carboxy function group, a carbonyl functional group or their derivatives such as carboxylic acid anhydride, lactone, or ether which are coupled with surface carbon atoms, therefore carbon content in this purified diamond is lower than that of natural diamonds.
This British Patent also describes that the synthesized diamond is a mass of interwinded diamond crystllites and corresponding to a particle size not greater than 0.01 μm (100 Å) of average diameter containing so many dislocations that defined crystal faces are not visible, and has no susceptible external crystal surface when inspected by an optical microscope having a power of ×100,000, and when anhydrous, not exhibits pyramid shape pursuant to natural diamond, individual diamond particle is 7×10−1 to 10−2, and also exhibits characteristic infra-red absorption peaks at the wave lengths 5,65 and 16.2 microns and broad bands of absorption at the wave lengths 2.8 to 3.5 microns, and a broad band of absorption at the wave length 9.2 9.8 microns when an hydrous, characteristic infra-red absorption peaks and bands of absorption at the wave lengths indicated when hydrated, and more intense absorption in the region of about 2.9 and 6.1 microns, in addition to the aforementioned the absorptions shown in an hydrous, state, and also describes that this new diamantiferous material, unlike most natural diamonds or man-made diamonds manufactured by other synthetic method, blackens when heated in an argon atmosphere at a temperature in the range from 850° C. to 900° C. for period of 4 hours, and as a result, this diamantiferous material can normally be recognisd by the loss of at least 5%, generally at least 8%, of its weight in the form of carbon monoxide, carbon dioxide, Water, and hydrogen.
Further, Japanese Laid-Open Patent Publication of Tokuhyou Shou 57-501080 by Japanese language of PCT WO 82/00458 which corresponding to U.S. Pat. No. 4,483,836 discloses a method of producing diamond and/or diamond-like modifications of boron nitride from a material to be transformed, in which, A method for producing diamond and/or diamond-like modifications of boron nitride by detonating in a container, a charge of a particulate admixture of 1% to 70% of an explosive (for examples cyclotrimethylenetrinitramine (hexogen), cyclo-tetramethylenetetranitramine (octogen), trinitrotoluene (trotyl), trinitrophenylmethylnitramine (tetryl), pentaerythritol tetranitrate (PETN), tetranitromethane (TNM) or mixtures of said explosives)and 99%to 30% of the material to be transformed, selected from the group consisting of: (a) carbon (such as hexagonal graphite, rhombohedral graphite, colloidal graphite, and pyrolytic graphite) to produce diamond,(b) boron nitride to produce diamond-like modifications of boron nitride, (c) carbon and boron nitride to produce a mixture of diamond and diamond-like modifications of boron nitride; and (d)additives (such as water, dry ice, liquid nitrogen, aqueous solutions of metal salts, crystal hydrates, ammonium salts, hydrazine, hydrazine salts, aqueous solutions of hydrazine salts, and liquid or solid hydrocarbons) inert to the material to be transformed, in an amount of 1 to 50% by weight of the charge, which endothermically evaporate and decompose beyond the front of a detonation wave, for cooling heated metal wall and the resulting high-pressure phase (the target product) upon impact compression, to preclude annealing of said phase and its re-conversion to the initial state, wherein said explosive upon detonation produces dynamic pressures varying from about 3 to 60 GPa and temperatures varying from about 2,000 degree K to 6,000 degree K and includes an inactive additive, such as water, ice, liquid nitrogen, metal salt solution, crystalline hydrate, ammonium salt, hydrazine, hydrazine salt, hydrazine salt solution, liquid hydrocarbon, or solid hydrocarbon, which is inactive and can be evaporated and decomposed over the wavefront of shock waves. As the explosive is combined with the carbon material to develop a preparation form, its detonation will be improved. For increasing the productivity of diamonds, the carbon material to be shock converted is added with another material such as a metal which can be heated by a temperature lower than that of the high pressure phase generated by the detonation. This allows the additive to decline the temperature in the high pressure phase hence inhibiting annealing and re-conversion (U.S. Pat. No. 3,401,019 and United Kingdom Patent No. 1,281,002).
And this Publication also discloses that the use as explosives, substances which upon detonation of a charge providing dynamic pressures of 3 to 60 GPa and temperatures of 2000 degree K to 6000 degree K, and such substances are, e.g. cyclotrimethylenetrinitramine (hexogen), cyclo-tetramethylenetetranitramine (octogen), trinitrotoluene (trotyl), trinitrophenylmethylnitramine (tetryl), pentaerythritol tetranitrate (PETN), tetranitromethane (TNM) or mixtures of said explosives, and maximum pressure is determined by the pressure in the chemical peak of the detonation wave, which for hexogen having a density of 1.6 g/cm3 is 60 GPa, and which for trotyl having a density of 0.8 g/cm3 is 3.0 GPa.
Such conventional shock compressing conversion methods of synthesizing diamonds using detonation of explosives explosion of include: (1) method of converting graphite to diamond by making collision a striking body accelerated by the detonation, into the graphite, as disclosed in, for example, Japanese Unexamined Patent Publication of Tokkai Hei 4-83525, (2) method of converting graphite to diamond by making collision a capsule loaded with graphite therein and being accelerated by the detonation, against a target surface for example pooled water surface, then picking up the submerged capsule in water and recovering object (synthesized diamonds) from the inside of the capsule, (3) detonating a mixture of a high-performance explosive and a graphite material to convert the graphite into a diamond form, and the like methods.
The method (1), which is a method comprising steps of colliding an accelerated object to a container of raw material then picking up the colluded container from in water to recover synthesized diamonds, allows the container and other instruments for the collusion to be employed only one time, it never permits to be used two or more times. Also, the amount of the explosive for the detonation is needed some tens of times greater than that of the graphite material corresponding to diamond amount. Accordingly, the method (1) will require more labors and costs for supplying a new set of the components and the explosive at each action. Equally, the method (2) requires more labors for provision of the accelerating arrangement. In addition, as the accelerating arrangement is broken up by the detonation, it has to be rebuilt thus increasing the overall cost. The method (3) employs non of the consumable arrangements but a detonation container in which the mixture of an explosive and a graphite material is detonated then synthesized diamonds are picked up from the products deposited on the inner wall of the container. It is hence necessary that the detonation container is tightly sealed off during the detonation and can be opened for taking up the products. Also, the detonation container has to be rigid enough strength to stand for the detonation and intricately arranged for replacing the air with an inactive gas in the interior or reducing the inner pressure to avoid combustion of the products at the detonation. As its detonation container has to be handled for opening and closing at every action of the detonation, the method (3) similar to the other methods (1) and (2) will also require more labors.
The detonation of an explosive easily produces a high pressure and a high temperature for conversion of the graphite structure of a carbon material into a diamond structure in a reactive system. However, as the inner pressure in a closed reactive system is increased, the temperature soars up. As explained, the heat (temperature) effectively acts on the conversion of the graphite structure into a diamond structure. Also, the high pressure has a primary role for conversion into the diamond structure. When the pressure is instantly released after the diamond synthesizing process while generated heat (temperature) is still remained in the reaction system, the remained heat (temperature) may act on the returning of the diamond structure to the graphite structure. The temperature acting on the returning of the synthesized diamond structure to the graphite structure is generally about 2000° C. in the reactive system when the high pressure has been declined to an atmospheric level. The speed of transmission of the shock waves generated by the detonation ranges commonly from 0.8 km/sec to 12 km/sec. It means that such high pressure is, in only short time, held in the reactive system of a common scale within 10−5 to 10−6 of a second. Particularly, the duration of maintaining the pressure at its higher level locally in every minimum reactive area is as short as 10−8 to 10−9 of a second. Since the graphite material is elastic and its storage resiliency (tan δ) or loss resiliency (tan δ″) for easing the effectiveness of the high pressure is not negligible, the high pressure in the reactive system may be maintained in a less period of the duration. It is hence difficult to quickly decline such high temperature to the atmospheric temperature passing through a temperature zone around 2000° C. which is a temperature for returning back the produced diamond structure to the graphite structure, if in the absence of momentary liberalization of the pressure.
There are also proposed methods for synthesizing diamonds in which a carbon material based on explosive is used. As a typical example, Japanese Unexamined Patent Publication of Tokkai Hei 3-271109 discloses a detonative synthesis method of diamond which is capable of plural desired times of explosions repeatedly and is capable of recovery reaction products easily. The method, which uses an organic explosive composition mixture having a negative value in of OB (Oxygen Balance) denoted by Exhibition (II) with regard to Exhibition (I) showing excess oxygen amount by gram unit in reaction of one gram explosive material,CxHyOzNw−>xCO2+y/2H2O+w/2N2−(2x+y/2−z)O2  (I)(OB; Oxigen Balance)=−16(2x+y/2−z)/Z  (II)(where M being the molecular weight of a chemical compound CxHyOzNw) in contrasting with the OB level being set to zero in common industrial explosive by mixing properly a negative OB combustible material and a positive OB oxygen contained inorganic salt, comprises steps of: preparing said organic explosive composition by mixing an explosive compound (such as tri-nitro-toluene TNT, cyclotetramethylene-tetranitroamine HMX, cyclotrimethylene-trinitroamine RDX, penta-erythritol-tetra-nitrate PETN, amine nitrate, amine perchlorate, nitro-glycerin, picric acid, or tetryl) with a combustible material (such as an oxygen reactable carbon precursor such as paraffin, light oil, heavy oil, aromatic compound, plant oil, starch, wood meal, or charcoal) to have an oxygen balance level of −0.25 to −1.2, the organic explosive composition, suspending said explosive composition horizontally at a depth of not smaller than 50 cm (for example, 120 cm) in the water a tube having either one or both ends thereof opened (for example, a steel cylindrical tube having an inner diameter of 27 cm, a length of 125 cm, and a thickness of 0.6 cm and arranged open at one end) and filled with the organic explosive composition (for example, weighted 10 g and consisting mainly of 76.2% of HMX, 19.5% of 2,6-dibrom-4-nitrophenol, and 4.3% of paraffin), detonating the tube a desired number of times by electrical energization of a detonator to synthesize diamonds in the water; draining the water and collecting a diamond contained product deposited at the bottom; and dissolving and removing byproducts such as metals and remaining graphite by a known manner of eliminating the metals with aqua regia or nitric acid and then the remaining graphite with a mixture of hydrochloric acid and nitric acid before treating with a mixture of hydrofluoric acid and nitric acid; washing with water and drying the product to obtain pure, synthesized diamonds (at a productivity of 5.2% based on HMX).
Japanese Laid-Open Patent Publication of Tokuhyou Hei 6-505694 by Japanese language of PCT WO 93/13016 which corresponding to U.S. Pat. No. 5,861,349 discloses a synthetic diamond-bearing material consisting essentially of aggregates of particles of a round or irregular shape, with an average diameter of the particles not exceeding 0.1.mm., the improvement wherein the material comprises: a) elemental composition (% by mass):
carbon 75 to 90,hydrogen0.6 to 1.5,nitrogen0.8 to 4.5,oxygenthe balance;    b) phase composition (% by mass): amorphous carbon 10 to 30, diamond of cubic crystal structure the balance;    c) a porous structure said material having pores with a volume of the pores being within about 0.6 to 1.0 cm3/l;    d) a material surface with 10 to 20% of the material surface being methyl, nitrile, first and second hydroxyl groups having different chemical shifts in an NMR spectrum and one or more oxycarboxylic functional groups selected from the group consisting of carbonyl groups, carboxyl groups, guinone groups, hydroperoxide groups and lactone groups 1 to 2% of the material surface being occupied by carbon atoms with uncompensated bonds; and    e) a specific surface area in a range of from 200 to 450 m2/g;            and a process for preparing a synthetic diamond-bearing material consisting essentially of:            (a) providing a pressure vessel with (i) a charge consisting essentially of at least one carbon-containing solid explosive or mixture of carbon-containing solid explosives, said charge having a negative oxygen balance, and (ii) a medium consisting essentially of gases and carbon particles ultra dispersed as a suspension in the gases in a concentration of about 0.01 to 0.15 kg/m3, said gases consisting essentially of oxygen in an amount of about 0.1 to 6% by volume and a balance of nitrogen or gases inert to carbon;    (b) closing the pressure vessel and detonating the charge, the detonating of the charge being initiated at a temperature of about 303 degree K. to 363 degree K in the absence from the charge of a carbon material other than the carbon-containing explosive or mixture of explosives to form the synthetic diamond-bearing material from decomposition products of the explosive or mixture of explosives and not from the carbon particles in the medium; and    (c) recovering the synthetic diamond-bearing material.
In Yokan Nomura & Kazuro Kawamura Carbon, vol. 22, No.2, pp.189–191 (1984)/, there are described some properties of soot produced in detonation of trinitrotoluene in an apparatus made from carbon steel. (The composition of the atmosphere is not reported). From the data of electron microscopy, this specimen mainly comprises a roentgen-amorphous phase of nondiamond carbon constituted by particles of 5 to 10 non flat carbon layers distributed chaotically so that no graphite phase is produced.
Another publication of theoretical investigations, Van Thiel, M. & Rec., F. H. J. Appl. Phys., vol. 62, pp. 1761–1767 (1987) considers some properties of carbon formed in detonation of trinitrotoluene. On the basis of calculation, the authors have made the assumption that the carbon formed under these conditions features excessive energy as against graphite by 1 to 2 kcal/mol. Proceeding from these data the assumption has been made that the carbon particles produced in explosion must have the size of the order of 10 nm.
Another prior art report is issued in N. Roy Greiner, D. S. Phillips, J. D. Johnson & Fred Volk, “Nature”, Vol. 333, 2nd, June 1988, pp. 440–442. This prior art discloses the properties of carbon generated by the detonation of an explosive material mixture composition of tri-nitro-toluene and RDX (60/40%), under an argon atmosphere at a room temperature. The condensed product generated by the detonation contains diamonds and non-diamond-transformed carbons, and crystalline analysis and X-ray analysis reveal that the amorphous carbon phase consists of a solid, spheroidal structure of about 7 nm in diameter with a curved belt form of about 4 nm in thickness. It is also described in the report that this non-diamond carbon has an interplanar spacing between completely amorphous graphite and randomly oriented graphite measured 0.35 nm thus having typical reflective (002) planes in an X-ray pattern.
Japanese Laid-Open Patent Publication of Tokuhyou Hei 7-505831 by Japanese language of PCT WO 94/18123 which corresponding to U.S. Pat. No. 5,916955 describes following instructions as in explanations of a diamond-bearing material comprising carbon, hydrogen, nitrogen and oxygen, wherein the material comprises, carbon of cubic crystal structure of 30 to 75% by mass, amorphous phase of carbon of 10 to 15% by mass, carbon of a non-diamond crystalline phase the balance, with a quantitative ratio of elements, carbon of 84 to 89% by mass, hydrogen 0.3 to 1.1% by mass, nitrogen of 3.1 to 4.3% by mass, oxygen of 2.0 to 7.1% by mass, and incombustible impurities of 2.0 to 5.0% by mass, the crystalline carbon phase having a surface containing methyl, carboxyl, quinone, lactone, ether, and aldehyde functional groups, the material having a unit surface of about 218 to 600 m2/g; and following instructions as in explanations of aforementioned diamond-bearing material.
Namely, this Patent Publication describes that the crystalline and roentgen-amorphous carbon phases are made up of compact spheroids of a diameter of some 7 nm and bent bands around 4 nm thick. The nondiamond form of carbon is characterized on the X-ray pattern by an inter-plane spacing of 0.35 nm typical of reflection (002) for the fully amorphous and randomly disoriented graphite.
This Patent Publication describes that the diamond carbon phase compact spheroids of a diameter of some 7 nm. In the studies by the method of electron diffraction, the following set of inter-plane reflections has been recorded: d=0.2058, 0.1266, 0.1075, 0.884, 0 and 0.636 nm which correspond to the reflection planes (111), (220), (311), (400) and (440) of the diamond.
This Patent Publication also describes that the product of the claimed invention was produced in detonation of an oxygen-deficient explosive in a closed volume in a medium inert towards carbon which is synthesized at a cooling rate of the detonation products of 200 to 600 degree/min.
This Patent Publication also describes that commonly use was made for the purpose of an explosive of the composition: trinitrotoluene/RDX (octogen, analogue of RDX) of 50/50 to 70/30. The material of the invention is a black powder with a unit surface of 218 to 6000 m2/g, a specific weight in the range from 2.2 to 2.8 g/cm3 and a humidity of 4.0%. The specific weight of the specimens is defined by the proportion of incombustible impurities, mainly iron. The proportion of incombustible impurities in the product of the invention claimed varies within the limits from 2.0 to 5.0%.
This Patent Publication also describes that the incombustible impurities include magnetite, an alpha-modification of iron and ferric carbide. From data of gamma-resonance spectroscopy, the following distribution of intensities in the spectrum takes place: the contribution of the lines of alpha-iron constitutes 29 to 43%, of magnetite is 36 to 48% and of the ions of ferric iron (represented by ferric carbide) is 16 to 27%. By the elemental composition, the product includes (% by mass) from 84.0 to 89.0 carbon, from 0.3 to 1.1 hydrogen, from 3.1 to 4.3 nitrogen; from 2.0 to 7.1% oxygen (by the difference). (The elemental composition is determined using the standard combustion technique of organic chemistry).
This Patent Publication also describes that Data of nitrogen and carbon distribution have been obtained using the method of X-ray photoelectron spectroscopy. It was found that the following relationship between the atoms of oxygen and carbon, nitrogen and carbon takes place in the source specimen: O/C=0.030 to 0.040, N/C=0.01 to 0.03. After etching the surface with argon ions these relationships changed: O/C=0.017 to 0.020, N/C=0.001 to 0.0005. This is indicative of the presence of oxygen-and nitrogen-containing groups on the surface of the particles. A low-molecular component of the claimed substance was separated by extraction with nonpolar solvents (tetrachlorated carbon, ether, n-hexane and benzene). The fraction of the total mass varies within the limits 0.36 to 1.13% and is a mixture of organic compounds. From the data of IR-spectroscopy, there was revealed the presence of such functional groups as OH, NH, CH2—, CH3—, CH— and —C—O—C— groups. These compounds are the products of condensation of the stable fragments of molecules in a detonation wave.
This Patent Publication also describes that information of the surface condition was obtained making recourse to the methods as follows. By the data of gas-chromatographic analysis, the following gases are separated when heating in a vacuum at 673 degree K during 2 hours: methane 0.03 to 0.47 cm3/g, hydrogen 0.03 to 0.30 cm3/g, carbon dioxide 0.02 to 0.84 cm3/g, oxygen 0.00 to 0.05 cm3/g and nitrogen 0–20 to 1.83 cm3/g. The total gas separation varies within the limits 0.36 to 2.98 cm3/g. These data show that the surface of the claimed product includes methyl (because methane is separated) and carboxyl (because separation of CO2 is detected) groups. On the basis of the data on gas evolution from specimens at the temperatures 573 to 773 degree K, activation energies were determined for a number of gases: 103.6 kJ/mol for carbon monoxide, 23.4 kJ/mol for carbon dioxide, 22.5 kJ/mol for nitrogen and 47.6 kJ/mol for methane. The values of the activation energy obtained point to that the evolved gases are not adsorbed by the surface but are rather formed in breaking of the chemically bonded surface groups. According to the data of polarographic studies, quinone, lactone, carbonyl, aldehyde and ether groups were present in all specimens. But methyl groups prevail in the product according to the invention, therefore the material features a water-repellent property. This, in turn, defines the sphere of application of the material in composities containing nonpolar components, such as rubbers, polymers, oils. Any chemical treatment materially influences the surface properties of the substance and the possibility of its use in one or another composite material. Distribution of the carbon forms in the substance of the present invention has been found by using X-ray photoelectron spectroscopy (XPES). From the data of XPES, C line Is is represented by a broad asymmetric peak with a halfbreadth of 4.1 eV, which, after being bombarded with argon ions narrows to 2.5 eV and takes the shape typical of graphite or finely dispersed coals. The surface charge is equal to zero, which is characteristic of electrical conductors. It may be assumed that the spectrumen volume is represented by the phase of nondiamond carbon and diamond carbon, the diamond carbon being distributed in particles. Information on the phase composition of the material of the present invention was obtained using the method of X-ray: phase analysis.
The X-ray patterns of the studied specimens contain, along with three lines relating to the diamond phase of carbon, reflection (002) of carbon and a broad maximum with d=0.418 nm relating to the roentgen-amorphous phase of carbon, the presence of this phase being stipulated by the conditions of synthesis. The presence of the latter maximum particularly distinctly shows up after partial oxidation of the substance with either air oxygen or an oxidizing mixture of acids).
This Patent Publication also describes that distribution of the material particles was found by the method of small-angle scattering. As follows from the curve, size distribution of the particles is characterized by a single maximum in the region between 40 and 50 A. And from these data the carbon phases are not divided by particle sizes. Investigation into the behavior of specimens heated in the air atmosphere showed that one broad exoeffect with a maximum at 683 to 773 degree K is observed on a DTA curve, which is indicative of a very high homogeneity of the material. It is not found possible to separate the material into nondiamond and diamond forms of carbon without destroying one of them. On the basis of the conducted investigations, the following particle structure of the material according to the invention can be assumed. A diamond nucleus in the center is surrounded by the roentgen-amorphous phase of carbon. The roentgen-amorphous carbon phase in contact with the nucleus comprises a roentgen-amorphous phase of diamond which passes through the roentgen-amorphous carbon phase into a crystalline phase of carbon. Surface groups are found on the surface of the crystalline carbon phase. The diamond-carbon material of the present invention is produced by detonating an oxygen-deficient explosive in a closed volume in a medium inert towards carbon at a cooling rate of the detonation products of 200 to 6000 degree/min in a conventional blasting chamber. The explosion temperature of the composition T/RDX 60/70 amounts to (depending on the calculation method) 3500 to 4000 degree K, and after the explosion the products are cooled down to 350 degree K. If we take the rate of cooling of the order of 7000 degree/min, then under these conditions a carbon phase will be formed containing 70 to 80% by mass-of-the cubic phase (diamond). But for realizing such cooling conditions, it is required that the volume of the blasting chamber exceed about one million times the volume of the exposive charge. In other words, in blasting a charge of 1 kg of explosive of the composition T/RDX 60/40 a blasting chamber of about 500 m3 is required, which is economically and technically inexpedient because of a high level of the product loss and low output. If, on the contrary, the cooling rate is decreased below 200 degree/min, then due to interaction with carbon dioxide and water vapors the product of the claimed invention has time to react with them, thus turning completely to CO.
This Patent Publication also describes that it is therefore necessary to provide a cooling rate which would be technically realizable and make possible to obtain the required relation between the carbon phases and a definite composition of the surface groups. All this permitted of using the material formed as a component of highly effective composite materials. The rate of gas cooling was adjusted by using different conditions of release of gases and varying the volumes of explosives and blasting chamber.